sign might be too dangerous or otherwise unwarranted. It is intended therefore to invoke particular caution. This sign is used as a direct replacement for the slash-through speed derestriction signs common in Europe and elsewhere. Speed limits are enforced in all areas of the country. Tolerance is about 6 km/h in urban areas and 9 km/h on highways depending on regulations of respective state such that driver driving on or below the tolerance speed will not receive a ticket. This is the case in South Australia and other states have similar tolerances. One exception is Victoria where they will deduct 2–4 km/h in from the speed reading such that reasonable doubt is credited to the driver. especially in light of the fact that earlier Australian Design Rules specified that vehicle speedometers may have up to 10% leeway in accuracy. This was updated in 2006 to require that the "speed indicated shall not be less than the true speed of the vehicle." Detection measures used are radar, LIDAR, fixed and mobile speed cameras (using various detection technologies), Vascar, pacing and aircraft. Default speed limits by state and territory Despite introduction of model national road rules by the states in 1999, Western Australia and the Northern Territory retain different default speed limits. The table below indicates the default speed limits along with typical school zone limits and the highest zone in each locality. In the external territories, and in some special cases (such as Lord Howe Island, NSW), the speed limits may differ significantly from those found across the rest of the nation. Limits for Learner, Provisional and Probationary licence holders The table below indicates the different speed limits that apply for each state's licence holders. The limits apply when the roads stated speed is above the licence's speed limit, e.g.: a person with a NSW P1 licence can drive at a max speed of 90 km/h on 100/110 km/h signed roads in any state. Conversely, a person with a Queensland provisional licence is not speed limited and can drive at the road's stated speed, even while in NSW where local provisional drivers are limited to 90 km/h. Limits for trucks and buses New South Wales has a limit of 100 km/h for heavy (more than 4.5 tonne) vehicles which is not a feature of the Australian Road Rules. Additionally particular heavy vehicles (some buses and vehicles more than 13.9 tonne) and